If the change in season has you suddenly feeling a bit more amorous, it’s not a coincidence, says Till Roenneberg, a professor in Munich who studies how biological rhythms affect our physiology and behavior. Turns out that during the autumn—when leaves change color and drift to the ground—we get depressed. In response, our brains up our supply of dopamine—a “happiness hormone”—which is what produces the tummy flutters so familiar to those in love. Plus, the fact that the weather's getting colder can't help but make snuggling irresistibly appealing.

The number of total knee replacement surgeries has soared 161.5% among Medicare participants over the past 20 years, a $5 billion annual tab that will continue to grow as Baby Boomers age, according to a new study. While the wider use of knee replacement is clearly good for those whose quality of life improves, some experts view it as another strain on government, individuals, and businesses struggling with health care costs. (Considering the surgery? Here's what Billie Jean King wants you to know.)

Consider this your permission slip to spend a few extra minutes outside during lunch today: New research from Copenhagen shows that low levels of vitamin D are associated with a markedly higher risk of heart attack and early death. Researchers looked at health info from 10,000 people to find that low levels of the sunshine vitamin compared to optimal levels are linked to 40% higher risk of ischemic heart disease, 64% higher risk of heart attack, 57% higher risk of early death, and to no less than 81% higher risk of death from heart disease. Check out our guide to getting enough vitamin D to help keep yourself safe.

Juliana Koo just turned 107 and has a few life lessons to share. When asked about her secret to a long life—a life that involved working for the United Nations and raising incredibly successful daughters—she said, “No exercise, eat as much butter as you like and never look backwards.”

Besides the obvious benefit to your cholesterol levels—let's be real, bacon’s not exactly a health food—there are tons of other reasons why eating less bacon (for whatever reason) is a good thing. Really, just look at #7. What’s not to like?